In wiring concrete decks, a frequent problem is that the pipe or conduit carrying many wires to a central point (e.g., power panel closet, fire alarm box, or center of an office or hotel room) must exit the poured concrete slab into the utilization room below the poured concrete deck. This conduit must be placed on the temporary “form” of metal or plywood that will support the wet concrete until it hardens, and will therefore end up embedded in the concrete slab.
However, the exit end of this conduit (i.e., at a room end) presents a problem, as it cannot be allowed to project out of the bottom plane (i.e., the bottom surface) of the form support deck; if it did, it means a custom hole in the support deck that must be carefully sealed to avoid a concrete leak. This is rarely done except when required, by exceptional circumstances, as much hand-work or labor is involved.
Instead, a small outlet box (e.g., preferably 6″×6″ or larger) is positioned face down on the deck form; it may be filled with foam, plastic or protected by a plastic cover to keep concrete out.
After the concrete hardens and the support or “form” deck is removed, the box is located in the ceiling from below, and broken into, and the required wires are pulled in. At this point, another box must be fastened over the original one and a large hole cut in this second box on the back surface, usually the same size as the embedded box. This is to provide an entry point for wires emanating from the concrete encased box and its conduits, and to provide termination and end support for pipes and/or cables running exposed on the underside of the new deck. It is not possible to access the sides of the embedded box in the concrete, and the cover where all these wires join must be removable, eliminating any possible cable access through, for example, a plain flat cover.
All of the above parts are now made by hand or modified at the site or shop from known, stock, electrical junction box parts.
The generally square shape of the recessed box opening is not optimal for pulling in wires. A bigger rectangle-like cover or opening as used on an electrical “LB” conduit fitting, (which has the same function of allowing wire pulls) would be much better, and a matching surface box to match that opening can then be attached to it, or over it.
Accordingly, it is a general object of the invention to provide a related method and apparatus for embedding an electrical junction box in concrete applications, such as decking or flooring, which simplifies the prior manufacturing process by eliminating several steps described above.
It is another general object to provide an improved process for obtaining wire pulls with such an electrical junction box.
It is a specific object to provide such an electrical junction box in which at least part of the electrical junction box can be pre-located prior to having concrete poured around the box.
It is a more specific object to provide an electrical junction box, commensurate with the above-listed objects, with two mating parts for use in managing transitions from conduit within concrete decks to cables outside the deck.